LeetCode: Single Number

Given an array of integers, every element appears twice except for one. Find that single one.

Note:
Your algorithm should have a linear runtime complexity. Could you implement it without using extra memory?

   int singleNumber(int A[], int n) {  
     int Xor = 0;  
     for (int i = 0; i<n; i++)  
     {  
       Xor ^= A[i];  
     }  
     return Xor;  
   }